Sheet-gripping mechanism of printing machines



. A. B. EVANS SHEET GRIPPING MECHANISM '0? PRINTING MACHINES June 16, 1925.

Filed Nov. 26, 1924 Inventor u S .M I Attorney- Patented June 16, 1925. I

assess seamstress revises, oil teats. teeters; tenet-emanate meat-men er "meme momma I Kpplieation men November as, 1924 Serial No. tsasm;

To, all whom it may concern:

Be it lcnown that I, ARTHURBUEROUGHES Evans, a sfubjectof the King at ,Great Britain and ,Ireland, residing at 7 Woodland Grove, Leeds, England, have invented certain new and useful Improvements. in Sheet-Gripping Mechanism of Printing Machines, of which the following is-a specificationz This invention relates to sheet fed printing machines of the kind iIiwhich the sheet is held to the sheet carrying cylinders, chains or reciprocating carriages or the like by means of grippers which nip the front edgeofthe sheets and hold, them upon gripping bars or pads or the like fitted to and -inovin*g with thesheet carrying cylins ders, chains er reciprocating lcarria ges or the like, or hold them to the leading edge of the sheet carrying cylinders where no bars, pads or the like are'provided. It is customary in such machines for anumber of these grip ers, each consistingiof a single element, to fie carried in spaced relation upon a shaft which extends across the sheet, each individual gripper being capable of angular adjustment on this shaft so that all the grippers may be adjusted to act with equal or uniform gripping pressure upon the sheet.

The present invention has for its object to overcome the difiiculty which is experienced in attaining and maintaining this uniform gripping pressure of the individual grippers, whether the grip be secured by positive or spring actuation ofthe shaft, owing to the delicacy of the required adjustment.

According to the present invention each individual gripper comprises two parts,-0ne of which, forming the gripper proper, is rotatably mounted upon the gripper carrying shaft whilst the other is secured adjustably upon the said shaft and is adapted upon partial rotation of the shaft, tomove the gripper proper from the gripping position in which it is maintained by a spring the strength of which corresponds to the pressure which the gripper is required to exert, which spring is sopositioned that the force which it exerts to maintain the gripper proper in the gripping position is relaxed when the gripper proper is moved from the said position.

According to the invention, moreover, the spring is advantageously connected between the twoparts of thegripper. It mamhewever, be otherwise mountedso. long as it acts upon the gripper. proper and is anchored in fixed relation. to the gripper carrying shaft. I W l When the grippers provided according to V the invention have been adjusted they willmaintain a uniform and equalpressure upon'uthe sheets presented to them netwith standi'ngvariations thickness or 'widths of thesheets to be printed, or accidents of printing. 1 p The invention is lierleinaftel' described; by w'ayof example, withreference to the accompanying drawings in which Fig. 1 isya -si de elevation of a gripper having a flat spring, the gripper being shown in section; r

- Fig. 2 a similar view of a gripper having a different form and arrangemeht of spring; j i

Fig. 3 is a similar view of a gripper show ing. another spring arrangement; and,

.Fig, 4 is a rear elevation of a gripper with a spring coiled about the gripper shaft. In carrying the invention into effect as illustrated in Figure 1, one part a of the gripper comprises a sleeve a adapted to be received upon the shaft 7) and to be secured thereto by means of a clamping screw a or like device adapted to cause a die a to grip the shaft 6. The other part 0 comprises the gripper proper in the form of a finger c of the usual construction, the rear portion of which is bifurcated and formed a flat spring d mounted upon a boss a of the part a by means of a screw a, the spring being adapted to engage at its extremity with the upper face a of the finger 0 In the construction illustrated in Figure 2, the main parts a and 0 are arranged as in the construction represented in Figure 1 but the fiat spring (5 is replaced by a, helical spring 6 connected at one end to a lug a on the part a, which lug is advantageously in a position oppositely disposed with reference to the projection a and at the other endto a lug 0 upon the under face 0 of the finger 0 the helical spring 6 being disposed in such manner that it is in tension.

In the construction shown in Figure 8, a helical spring 7 is mounted, in such manner as to be in compression upon and between two oppositely disposed lugs 66 0, provided respectively upon the part a and upon the upper face 0 oi the finger 0 With reference to Figure 4 the main parts a and c are provided as hereinbefore described but a helical torsion spring g is used, which spring 9 is mounted loosely upon the shaft 6 in position adjacent one eye 0 of-the part 0, one end of the spring 9 being bent parallel with the shaft Z) so as to engage within a hole 0 in the eye 0 and the other end being likewise provided for engagement within a hole [L2 in a collar h mounted upon the shaft 6 and fixed thereto by means of a pin 71 or other suitable device. The spring 9 is of such form that the finger o of the part 0 tends to press against the projection a of the part a.

In order to set a compound gripper provided according to the invention, the shaft 7) is moved to the position it occupies when the gripper is closed, the screw (1- or like device is loosened so that the die a ceases to grip the shaft 7), the finger 0 of the gripper proper 0 is closed upon the sheet after insertion of a thin piece of material at the point of contact of the projection a with the under face 0 of the finger c and the screw (4 or like device is tightened so that the die a again grips the shaft 7) while it is still in the position before referred to.

The thin piece of material is then removed from between the projection a and the lower face 0" of the finger 0 the finger 0 thus being allowed to press freely upon the sheet under the action of the spring the strength of which corresponds to the gripping pressure.

I claim:

1. Sheet gripping means for printing presses comprising a rock shaft, a gripping finger loosely mounted on said shaft, a col.- lar adjustably secured to the shaft and having apart projecting beneath said finger and forming a stop for the same, and a salin normall' holdin the fin er a ainst b D 1) D said stop.

2. Sheet gripping means for printing presses comprising a rock shaft, a gripping linger loosely mounted on said shaft, a collar adjustably secured to the shaft and having a part project-ing beneath said finger and forming a stop for the same, and a spring interposed between the collar and linger and normally holding themfinger against said stop.

ARTHUR BURROUGHES EVANS 

